Most of the biomedical devices are manufactured from polymers and metals that are far from being biocompatible. Instead of developing new biomaterials, surface coating with polymeric thin films represents a convenient method for their modification and protection.
Polymeric thin film coatings represent a practical alternative to surface modifications since they preserve the properties of underlying materials while allowing, through a judicious choice of the coating method and polymer, to control macroscopic surface properties such as biocompatibility, electrical conductivity, specific optical properties, hardness/erosion resistance, and adhesion. Amongst the various known coating techniques, chemical vapor deposition (CVD) has gained substantial interest in recent years since (i) it proceeds at room temperature in the absence of solvent, and (ii) produces deposited films of uniform thickness with an excellent thickness and conformality control, as well as polymer purity. One of the most widely studied chemical vapor deposited family of polymers is the family of parylene (poly-paraxylylene) polymers, which, due to their excellent electrical insulation, low dielectric constant, barrier and chemical/thermal stabilities, and biocompatibility properties have found a wide use in electronic and biological/medical applications.
However and generally speaking, parylene coatings have a highly hydrophobic non-functional nature and their chemically stable surfaces do not fully satisfy attractive properties such as antibiofouling, water wettability, and lubricity properties necessary for a wide range of biological applications.
Accordingly, there is an urgent need for developing simple, cost effective, and reproducible methods that will enable the incorporation of chemically reactive functional groups or nanostructures onto parylene film surfaces. This step is essential to infer new properties to parylene films and, consequently to any film of the numerous other known polymer coatings that possess similar surface properties, thus greatly expanding their scope of potential applications.